In some cases, a definition or information of a document includes a relation among a plurality of files. For example, in the case of extensible markup language (XML) files, a relation between files is defined by describing an Xlink indicating a linked-to file in a linked-from file.
When a content of an XML file is updated, an information management system that manages XML files exclusively locks all files related to the XML file to be updated, and the information management system analyzes all exclusively locked files to check consistency between the file to be updated and the related files. If the check indicates good consistency, the information management system updates the content of the file. More detailed information about this technique may be found, for example, in Japanese Laid-open Patent Publication No. 2006-107215.
However, the processing load in checking the consistency between the file to be updated and related files increases with the total number of related files. That is, because the information management system analyzes all related files to check the consistency between the file to be updated and the related files, the processing load of checking the consistency increases with the number of files.
Note that not only when a file is updated, but when a file is deleted, a similar problem may occur.